Maryellen Guerriero of Seaford, the sister of slain ATF agent John Capano, was one of more than 60 people attending a forum Thursday on prescription drug abuse.

Guerriero, 54, said she has joined Nassau County Executive Edward Mangano's prevention-minded task force on the issue.

"Nobody should fear going to the pharmacy; to be afraid to go there to get medicine and never come back," she said.

Off duty on Dec. 31, Capano was shot and killed while struggling with a robbery suspect outside a pharmacy on Merrick Road in Seaford, his hometown.

The forum at the Morrelly Homeland Security Center in Bethpage was directed mainly at pharmacists, but there were also police officers and representatives from security firms, hospitals, a university, Nassau's Department of Social Services and the state Inspector General's Office.

The keynote speaker was Landon Gibbs, a security specialist with Purdue Pharma, the Stamford, Conn.-based manufacturer of OxyContin, one of the world's most-abused painkillers.

Gibbs said many people still don't see abuse of prescription drugs as something bad, thinking "it's just a pill, it's not real drugs."

He talked about the many ways the drugs can kill, especially in combination with alcohol and other pills. And he urged pharmacists to be wary.

"Sometimes you must second-guess a prescription," he said. "Call the doctor. Take notes."

He referred his audience to RxPatrol, an Internet information clearinghouse for pharmacists and law enforcement agencies that also allows the public to report prescription drug crimes.

Nassau Det. Sgt. John Giambrone, the robbery squad commander, said the department recently added pharmacies to a list of potential targets that includes banks, armored cars and jewelry stores.

The department, he said, has forged an information-sharing partnership with local businesses on crime and other concerns stemming from prescription drug abuse.

The number of people arrested so far this year in Nassau for forging prescriptions for painkilling opiates has quadrupled compared with the first six weeks of 2011, officials said recently.